Abstract The Sahara, one of the most extreme environments on Earth, constitutes an unexplored source of alkalitolerant actinobacteria. In this work, we studied the diversity of alkalitolerant actinobacteria in various soils collected from different regions of the Algerian Sahara. A total of 29 alkalitolerant actinobacterial strains were isolated by using a complex agar medium. The diversity of these actinobacteria was evaluated using a polyphasic approach, which included morphological, chemotaxonomic, physiological (numerical taxonomy) and 16S rRNA gene analyses. The isolates which were assigned to the genus Nocardiopsis, shared relatively low 16S rRNA gene sequences similarities compared to closely related species suggesting that they belonged to putatively new species. All of the strains were tested for antibiotic activity against a broad range of microorganisms and screened for genes encoding polyketide synthases and non-ribosomal peptide synthetases and found to have the potential to produce secondary metabolites. Consequently, the study supports the view that extreme environments contain many novel actinobacteria, which represent an unexplored source for the discovery of biologically active compounds.

中文翻译：

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阿尔及利亚撒哈拉土壤耐碱放线菌的分离、分类及拮抗特性

摘要 撒哈拉沙漠是地球上最极端的环境之一，是一种尚未开发的耐碱放线菌来源。在这项工作中，我们研究了从阿尔及利亚撒哈拉沙漠不同地区收集的各种土壤中耐碱放线菌的多样性。使用复合琼脂培养基共分离出 29 株耐碱放线菌菌株。使用多相方法评估这些放线菌的多样性，包括形态学、化学分类学、生理学（数值分类学）和 16S rRNA 基因分析。分配给诺卡氏菌属的分离株与密切相关的物种相比具有相对较低的 16S rRNA 基因序列相似性，表明它们属于推定的新物种。测试了所有菌株对多种微生物的抗生素活性，并筛选了编码聚酮合酶和非核糖体肽合成酶的基因，发现它们具有产生次级代谢物的潜力。因此，该研究支持极端环境包含许多新的放线菌的观点，这些放线菌是发现生物活性化合物的未开发来源。